The present invention relates to devices for treating fluids, such as water, and more particularly, to fluid treatment devices which are powered to provide electrical and magnetic fields in the fluid.
Fluid treatment with DC-powered solenoid coils has been used for many years. Such an arrangement is shown in U.S. Pat. No. 4,938,875. The DC power can be provided by a DC source (battery) or a rectified AC source. For example, U.S. Pat. Nos. 5,702,600; 6,063,287 and 6,146,526 have modified the AC method by using only a rectified half-wave to generate the DC power (without a smoothing power capacitor) and letting the coils ring with the current closed off for the second half wave. During the no-current period, the coils will ring at their resonant frequency (which can be modified by the addition of a small amount of capacitance) and emit a high frequency field into the fluid to be treated. In the '600 patent, a diode is used to rectify the wave and in the '287 patent, a triode is used to rectify the wave.
Use of a rectified (half wave) AC current for providing the DC power is inefficient, decreases the life of the transformer used in such circuits, and results in an unfavorable power factor.
While the first half wave is used in an almost purely inductive load in the coils, creating electromagnetic fields in the fluid, the second half wave is not used at all. This creates an inefficient and unbalanced load on the transformer.
Since only half of the wave is used, the transformer continually runs at magnetic saturation rather than operating in its design region. Operating a transformer at saturation will result in increase eddy current losses and hysteresis losses. The combination of excess heat generation and operating at magnetic saturation significantly reduces efficiency and negatively affects transformer life.
While the '600 and '287 patents further describe using a full wave rectifier to power the coils, such an arrangement also has problems. With full wave rectification, the coil ring is limited by the other half of the AC cycle. Devices built using this design will have a weak and truncated ring.
It would be an advance in the art if a fluid treatment device were provided that addressed the above described problems.